CH 1 - Wine Composition & Chemistry

Question 1

What are the 5 major components of wine?

Answer 1

Water, alcohol, acid, sugar, phenolic compounds

Question 2

Wine is a ______ blend of _______ that give its visual, olfactory and tactile characteristics

Answer 2

Complex, Chemicals

Question 3

Where do many of the chemical compounds found in wine originate from?

Answer 3

The grapes. But others are created during the fermentation process through the action of yeast cells

Question 4

What happens to the compounds over time as a wine ages?

Answer 4

The concentrations of some compounds increase as wine ages, while others decrease with time, resulting in a wine’s ever-changing character

Question 5

What percentage is water in wine?

Answer 5

80 - 90%

Question 6

Where does the water in wine come from?

Answer 6

Primarily from the grapes. But small amounts may be added during winemaking

Question 7

What percentage is alcohol in wine?

Answer 7

10 - 15%

Question 8

What is the primary kind of alcohol found in wine?

Answer 8

Ethyl alcohol or ethanol

Question 9

How is ethanol produced in wine?

Answer 9

It is produced during fermentation

Question 10

What are other types of alcohol that are in wine in smaller amounts?

Answer 10

Gylcerol, Methyl Alcohol (methanol), fusel alcohols (fusel oils or higher alcohols)

Question 11

Ethanol is a volatile compound that evaporates easily. When wine evaporates, what does it do with the wine’s aromas?

Answer 11

Carries the wine’s aromas to the nose.

Question 12

What sensation does alcohol create on the palate?

Answer 12

Weight or body

Question 13

What are “tears” or “legs”?

Answer 13

When swirled in the glass, high levels of alcohol result in slow, thick-appearing tears or legs

Question 14

What percentage of wine’s volume does acid make up?

Answer 14

0.5 to 0.75 %

Question 15

What are the 6 principal acids found in wine?

Answer 15

Tartaric acid, Malic acid, Citric Acid, Lactic Acid, Acetic acid and Succinic acid

Question 16

What are 4 grape acids (found in grapes)?

Answer 16

Tartaric Acid, Malic Acid, Citric Acid, Succinic Acid

Question 17

What are the 3 fermentation acids?

Answer 17

Lactic Acid, Acetic Acid, Succinic Acid

Question 18

What is the most prevalent acid found in grapes and wine?

Answer 18

Tartaric Acid

Question 19

Which acid has the strongest pH and also forms solid crystals called tartrates or wine diamonds?

Answer 19

Tartaric Acid

Question 20

What is Malic acid?

Answer 20

A sharp-tasting acid frequently associated with green apples

Question 21

Which type of grapes are high in Malic acid?

Answer 21

Underripe and cool-climate grapes

Question 22

Malic acid decreases as grapes ______ on the vine

Answer 22

Ripen

Question 23

Which type of grapes are low in Malic acid?

Answer 23

Overripe grapes and grapes grown in hot climates

Question 24

What winemaking technique can help with high Malic acid?

Answer 24

Malolactic fermentation

Question 25

How is Citric Acid used in wine?

Answer 25

It is sometimes added to increase total acidity, but its distinctive citrus flavors make it generally unsuitable for quality wines.

Question 26

Is Citric Acid considered a normal component of grapes?

Answer 26

No, it exists in such minute quantities that specialized equipment is required to measure it. It has no sensory impact on the majority of wines

Question 27

How is Lactic acid created in wine?

Answer 27

It is not found in grapes; it is created by lactic acid bacteria, which converts Malic acid into lactic acid during malolactic fermentation. It is also created in small amounts during primary fermentation

Question 28

What impact does lactic acid have on wine?

Answer 28

It is less intensely acidic than Malic acid, and wines tend to be softer and smoother in mouthfeel

Question 29

Acetic acid is found in most types of what?

Answer 29

Vinegar

Question 30

When is acetic acid created?

Answer 30

A small amount is created during fermentation

Question 31

Acetic acid in higher concentrations can have what harmful effect on wine?

Answer 31

At higher concentrations, a chemical reaction occurs between ethanol and oxygen caused by the harmful bacteria called acetobacter.

Question 32

What is acetobacter?

Answer 32

It is a harmful bacteria that causes a chemical reaction between ethanol and oxygen, which can make a wine unpleasant and undrinkable

Question 33

What is Succinic acid?

Answer 33

It is a minor component of grapes and a by-product of normal alcoholic fermentation

Question 34

What kind of flavor does Succinic acid have?

Answer 34

It has a sharp, slightly bitter and salty flavor

Question 35

What is Total Acidity (TA)?

Answer 35

The volume of all acids in the wine

Question 36

What is pH in regards to wine?

Answer 36

The pH level of wine represents the combined chemical strength of the acids present

Question 37

What are the typical levels of pH in wine? Which is considered high and low?

Answer 37

Wine measures between 2.9 (stronger) and 3.9 (less acidic)

Question 38

How much sugar do grapes normally contain?

Answer 38

Contain 15 - 28% at harvest

Question 39

What are the 2 sugars found in grapes at harvest?

Answer 39

Glucose, Fructose

Question 40

Glucose and Fructose are highly fermentable ________ commonly known as _____ _____

Answer 40

Monosacharides, simple sugars

Question 41

What is the process for converting sugar into alcohol?

Answer 41

During fermentation, yeast converts these sugars into ethanol, turning grape juice into wine. If yeast is able to finish its job, the wine will be fermented to dryness

Question 42

Wines that have less sugar than a person can taste as are described as?

Answer 42

Dry

Question 43

What are the levels of sweetness in wine?

Answer 43

Off-dry (medium-dry), medium sweet or sweet

Question 44

A small amount of sweetness can be added to balance what in wine?

Answer 44

To balance high acidity

Question 45

What phenolic compound give red wine its color?

Answer 45

Anthocyanins

Question 46

What is the color range for Antocyanins?

Answer 46

From blue, to purple, to red

Question 47

The _____ acidic wines appear ______ in hue

Answer 47

More, redder

Question 48

The _____ acidic wines appear _____ in hue

Answer 48

Less, bluer

Question 49

What phenolic compound gives the yellow pigments to white wines?

Answer 49

Flavonals

Question 50

White wines from sunnier climates have a more ______ color than white wines from cooler climates

Answer 50

Golden

Question 51

What phenolic compound is found in the skins, seeds and stems of the grapes?

Answer 51

Tannins

Question 52

Where else are tannins found?

Answer 52

In oak and oak barrels

Question 53

What sensations does tannins create in the mouth?

Answer 53

They create the textural, drying sensation in the mouth

Question 54

What phenolic compound is found in oak?

Answer 54

Vanillin

Question 55

What phenolic compound has beneficial health effects in humans?

Answer 55

Reservatrol

Question 56

Where are the majority of phenolic compounds concentrated?

Answer 56

In the skin and seeds

Question 57

Why are red wines richer in phenolic compounds?

Answer 57

Because red wines are fermented in contact with the grape seeds and skins

Question 58

Which phenolic compounds polymerize or combine into longer molecule chains that become too heavy to stay suspended in the liquid and drop to the bottom as sediment?

Answer 58

Tannins and pigments

Question 59

The production in wine has what effect on the wine?

Answer 59

The wine is lighter in color and less astringent

Question 60

What are oxidized alcohols called that form when wine is exposed to air?

Answer 60

Aldehydes

Question 61

Which wines are made in an oxidized manner?

Answer 61

Sherry and Medeira

Question 62

What is the term when a wine has been encouraged to develop aldehydes?

Answer 62

Maderized

Question 63

What is the most common form of aldehyde found in wine?

Answer 63

Acetaldehyde

Question 64

What form of alcohol has been oxidized when acetaldehyde is created?

Answer 64

Ethanol

Question 65

What type of wine does Acetaldehyde give its distinctive aroma to?

Answer 65

Sherries

Question 66

What compound is molecules that result from the joining of an acid and an alcohol?

Answer 66

Esters

Question 67

What is one of the most common Esters found in wine?

Answer 67

Ethyl acetate

Question 68

What acid and alcohol combine in creating the ester Ethyl acetate?

Answer 68

Acetic acid and Ethanol

Question 69

At low concentrations, what aromas does Ethyl acetate impart on wine? At high concentrations?

Answer 69

Fruity, flowery aroma; faulty aromas of nail polish remover, varnish or glue

Question 70

What dissolved gas promotes the chemical reaction called oxidation?

Answer 70

Oxygen

Question 71

What gets added during the winemaking process in order to absorb free oxygen molecules?

Answer 71

Sulfur

Question 72

What dissolved gas is also found in wine and is a natural by-product of fermentation?

Answer 72

Carbon dioxide

Question 73

What chemical compound is added to wine to keep them stable after fermentation?

Answer 73

Sulfites

Question 74

What chemical is also a natural byproduct of fermentation and found in minute quantities?

Answer 74

Sulfur

Question 75

In the US, if a wine contains more than _____ ppm of sulfur dioxide, a label saying "Contains Sulfites" is required

Answer 75

10

Question 76

Highly volatile acid, often found in vingegar

Answer 76

Acetic acid

Question 77

Main type of potable alcohol in wine

Answer 77

Ethanol (Ethyl Alcohol)

Question 78

An acid that tastes like green apples

Answer 78

Malic acid

Question 79

Most prevalent acid found in both grapes and wine

Answer 79

Tartaric acid

Question 80

Another term for tartrates

Answer 80

Wine diamonds (tartaric acid crystals)

Question 81

Conditions that can lead to a drop in malic acid

Answer 81

Warm/hot climate The ripening phase Over-ripe grapes Malolactic Fermentation

Question 82

Acid not found in grapes, but often produced during secondary fermentation (mlf)

Answer 82

Lactic acid

Question 83

Acid that is both a minor component of grapes, and a by-product of normal alcoholic fermentation

Answer 83

Succinic acid

Question 84

Typical range of pH for most wines

Answer 84

2.9 to 3,9

Question 85

Two main fermentable sugars found in grapes

Answer 85

Glucose and fructose

Question 86

Sugar remaining in a wine post-fermentation

Answer 86

Residual sugar

Question 87

Compounds that give red wine its color

Answer 87

Anthocyanins

Question 88

Yellow pigments found in white wines

Answer 88

Flavonols (flavones)

Question 89

Sources of tannin

Answer 89

Seeds, skins, and stems of grapes | Oak barrels / other oak products

Question 90

Compound found in red wine known for health benefits

Answer 90

Resveratrol

Question 91

What is meant by "polymerization"

Answer 91

When molecules (such as tannins) combine into longer molecule chains

Question 92

Oxidized alcohols

Answer 92

Aldehydes

Question 93

Molecules that result from the joining of an acid and an alcohol

Answer 93

Esters

Question 94

Chemical reactions resulting from dissolved oxygen

Answer 94

Oxidation

Question 95

In the US, wines containing more than ____ ppm of sulfur dioxide must carry a warning label

Answer 95

10